A group of about 40 people sued Japan Atomic Power Co. on Tuesday seeking a provisional court order not to restart two reactors at its Tsuruga nuclear power plant on the Sea of Japan in Fukui Prefecture.
In the suit filed with the Otsu District Court, the plaintiffs argue that Lake Biwa, Japan's biggest lake and source of water for the Kansai region centering on Osaka, could be contaminated and residents could be endangered if a nuclear accident occurs at the plant.
Currently the plant's two reactors, one with output capacity of 357,000 kw and the other with capacity of 1.16 million kw, are shut down for regular checkups.
The plaintiffs, mainly residents of Shiga Prefecture just south of Fukui Prefecture, insist that the Tsuruga plant was built on a site with a fault below it, leaving it susceptible to a severe accident.
They say the smaller No. 1 reactor has become degraded as more than 40 years have passed since it started operating in 1970.
The facility is also vulnerable to tsunami, they say.
They argue that regular checks are conducted under the government's present safety and technological standards that were proven insufficient by the crisis at the Fukushima No. 1 nuclear power plant.
The residents also contend that the two reactors should remain shut down until the government gets to the bottom of the Fukushima crisis and they undergo regular checks to be under fresh safety standards.
Japan Atomic Power declined to comment on the lawsuit, saying it was not aware of the details.
The No. 1 reactor's checkup is to be completed in March.